About a week ago announced a mini-expansion for Europa Universalis IV, Res Publica. It focuses on deepening the mechanics involved in republics and elective monarchies.
Available some time this summer.
Europa Universalis IV is available now at http://pdxint.at/OO9ygi
If you want to watch these

I\'ve been playing Total War: ROME II with the Eras of Rome mod on which is an Italian Wars scenario mod! Set in the world of Ancient Italy, before Rome ruled the world, italy is made up of small city-states whose fate you can decide.
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Link to mod:
http://steamcommunity.com/sh